New Technology More Than Doubles Success Rate for Blood Clot Removal

In cases of ischemic stroke, where a blood clot obstructs oxygen supply to the brain, time is critical. The faster the clot is removed and blood flow restored, the more brain tissue can be saved, improving the patient’s chances of recovery. However, existing technologies are only able to successfully clear clots on the first attempt about half the time, and in roughly 15% of cases, they fail entirely. A newly developed clot-removal method has now demonstrated over twice the effectiveness of current approaches. This breakthrough could greatly improve outcomes in treating strokes, heart attacks, pulmonary embolisms, and other clot-related conditions.

Clots are bound together by fibrin, a durable, thread-like protein that traps red blood cells and other particles, forming a sticky mass. Conventional clot-removal techniques involve threading a catheter through the artery to either suction out the clot or snare it with a wire mesh. Unfortunately, these methods can sometimes break the fibrin apart, causing clot fragments to dislodge and create blockages elsewhere in the body. Researchers at Stanford Engineering (Stanford, CA, USA) have developed a novel solution called the milli-spinner thrombectomy, which has shown significant promise in outperforming current technologies across multiple clot-related conditions.

This new technique is built on the researchers’ prior work with millirobots—tiny, origami-inspired robots designed to move through the body for therapeutic or diagnostic purposes. Initially designed as a propulsion device, the milli-spinner's rotating, hollow body—featuring slits and fins—also generated localized suction. Upon observing this unexpected effect, the team explored its potential for clot removal. Testing the spinner on a blood clot revealed a visual change from red to white and a substantial reduction in clot size. Encouraged by this unprecedented response, the team explored the mechanism behind it and refined the design through hundreds of iterations to maximize its performance.

Like traditional methods, the milli-spinner is delivered to the clot site via a catheter. It features a long, hollow tube capable of rapid rotation, with fins and slits engineered to generate suction near the clot. This setup applies both compression and shear forces, rolling the fibrin into a compact ball without fragmenting it. The suction compresses the fibrin threads against the spinner tip, and the spinning motion creates shear forces that dislodge the red blood cells. These cells, once freed, resume their normal circulation. The condensed fibrin ball is then drawn into the milli-spinner and removed from the body.

In a study published in Nature, the team demonstrated through flow models and animal trials that the milli-spinner dramatically outperformed existing treatments, successfully reducing clots to just 5% of their original size. Aware of the potential benefits for patients with stroke and other clot-related illnesses, the researchers are pushing to make the milli-spinner thrombectomy available for clinical use as soon as possible. They have founded a company to license and commercialize the technology, with clinical trials already in the planning stages. In parallel, the team is developing an untethered version of the milli-spinner capable of navigating blood vessels autonomously to find and treat clots. They are also exploring new applications of the device’s suction capabilities, including the capture and removal of kidney stone fragments.

“For most cases, we’re more than doubling the efficacy of current technology, and for the toughest clots – which we’re only removing about 11% of the time with current devices – we’re getting the artery open on the first try 90% of the time,” said co-author Jeremy Heit, chief of Neuroimaging and Neurointervention at Stanford and an associate professor of radiology. “It’s unbelievable. This is a sea-change technology that will drastically improve our ability to help people.”

“What makes this technology truly exciting is its unique mechanism to actively reshape and compact clots, rather than just extracting them,” added Renee Zhao, an assistant professor of mechanical engineering and senior author on the paper. “We’re working to bring this into clinical settings, where it could significantly boost the success rate of thrombectomy procedures and save patients’ lives.”

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Stanford Engineering